Detection of paramagnetic spins with an ultrathin van der Waals quantum sensor

Abstract

Detecting magnetic noise from small quantities of paramagnetic spins is a powerful capability for chemical, biochemical, and medical analysis. Quantum sensors based on optically addressable spin defects in bulk semiconductors are typically employed for such purposes, but the 3D crystal structure of the sensor inhibits the sensitivity by limiting the proximity of the defects to the target spins. Here we demonstrate the detection of paramagnetic spins using spin defects hosted in hexagonal boron nitride (hBN), a van der Waals material which can be exfoliated into the 2D regime. We first create negatively charged boron vacancy (V${}_{\mathrm{B}}^{-}$) defects in a powder of ultrathin hBN nanoflakes ($<10$~atomic monolayers thick on average) and measure the longitudinal spin relaxation time ($T_1$) of this system. We then decorate the dry hBN nanopowder with paramagnetic Gd${}^{3+}$ ions and observe a clear $T_1$ quenching, under ambient conditions, consistent with the added magnetic noise. Finally, we demonstrate the possibility of performing spin measurements including $T_1$ relaxometry using solution-suspended hBN nanopowder. Our results highlight the potential and versatility of the hBN quantum sensor for a range of sensing applications, and pave the way towards the realisation of a truly 2D, ultrasensitive quantum sensor.

19 pages, 11 figures

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• Electric Field Effect in Atomically Thin Carbon Films
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• Coupling spin defects in hexagonal boron nitride to monolithic bullseye cavities
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• Greatly Enhanced Emission from Spin Defects in Hexagonal Boron Nitride Enabled by a Low-Loss Plasmonic Nano-Cavity
• Method for in-solution, high-throughput T1 relaxometry using fluorescent nanodiamonds

Cited by in corpus (13)

• Quantum sensing and imaging with spin defects in hexagonal boron nitride
• Multi-species optically addressable spin defects in a van der Waals material
• Quantum Optics Applications of Hexagonal Boron Nitride Defects
• Nanotube spin defects for omnidirectional magnetic field sensing
• Temperature dependent spin-phonon coupling of boron-vacancy centers in hexagonal boron nitride
• Photonics in Flatland: Challenges and Opportunities for Nanophotonics with 2D Semiconductors
• Optimisation of electron irradiation for creating spin ensembles in hexagonal boron nitride
• Coherent Spins in van der Waals Semiconductor GeS2 at Ambient Conditions
• Understanding Decoherence of the Boron Vacancy Center in Hexagonal Boron Nitride
• A charge transfer mechanism for optically addressable solid-state spin pairs
• Multi-wavelength Spin Dynamics of Defects in Hexagonal Boron Nitride
• Spin-Phonon Relaxation of Boron-Vacancy Centers in Two-Dimensional Boron Nitride Polytypes
• All-optical magnetic imaging with spin defects in van der Waals materials at Angstrom-scale